Radiator Tube

ABSTRACT

A radiator tube ( 111 ) having a portion at each end which is adapted to be received in a header tank of a radiator and an intermediate portion between the ends, said intermediate portion having a cross section defined by a pair of side walls ( 121 ) and a pair of end walls ( 123 ), the side walls are generally parallel and have a spacing between them which is less than the spacing between the end walls, the side walls supporting a set of generally parallel fins ( 113 ), each fin extending laterally from the tube, each fin having an inner side edge thermally communicating with the respective side wall of the tube and an outer side edge ( 119 ) in a substantially spaced parallel relationship with the inner side edge, a forward edge ( 115 ) and a rear edge ( 117 ), said forward edge having an arcuate configuration taking the form of a continuous curve extending from the forward most edge of the fin to the outer side edge.

FIELD OF THE INVENTION

This invention relates to radiator tubes and in particular finned radiator tubes.

BACKGROUND

The finned radiator tubes to which the invention relates comprise tubes having ends which are adapted to be receivable in the header tanks of the radiator and have an intermediate portion between the ends which supports a set of fins. The invention particularly relates to such tubes where the intermediate portion has a generally rectangular configuration and where the fins are supported along the sides of the tubes which have the greater width. The fins can be formed as individual fins or alternatively may be formed from a folded length of material bonded to the tube. In such tubes the ends have a circular cross-section and are received in apertures provided in the respective wall of the respective header and each aperture is usually associated with a seal which sealingly retains the tubes within the tank.

The cross section of examples of finned radiator tubes according to the prior art to the present invention are illustrated at FIGS. 1 and 2 of the accompanying drawings. FIG. 2 is an example of conventional practice where the fins 13 have a generally rectangular configuration and where the forward and the rear edges 15 and 17 respectively are generally in line with the forward most and rear most end faces of the tube 11 respectively. A difficulty which has been encountered with such fins relates to the tendency for the spaces between adjacent fins to become clogged by debris and the like. A development of the prior art shown at FIG. 2 comprises an arrangement as shown at FIG. 1 which is the subject Australian patent specification AU-B-40475/93. In that arrangement the forward and trailing edges 15 and 17 respectively of the fins have been angled in an acute manner relative to the major axis X of the tubes between the end faces of the tube. The arrangement as shown at FIG. 1 has been introduced primarily for the purposes of reducing the collection of debris between the fins.

It has been found that both of the prior art arrangements as referred to above and as shown at FIGS. 1 and 2 present a significant difficulty when it becomes necessary to service a radiator core incorporating such radiator tubes. The removal and replacement of radiator tubes from and into the of a radiator core requires a considerable amount of manipulation and the application of considerable manual force. This manipulation is usually effected by personnel using their bare hands. Finned radiator tubes of the form as shown at FIGS. 1 and 2 present sharp edges which are created at the junctions 23 between the leading and trailing edges 15 and 17 and the side edges 19 of the fins 13. The presence of such sharp edges greatly increases the likelihood of injuries to the hands of the personnel during the removal and subsequent reinsertion of the tube. Furthermore because of the nature of the action being applied in removing and installing the radiator tubes it is not practical for an operator to use gloves or like protective means because the operator is very reliant upon their sense of touch to be aware of the action being undertaken and to determine whether the tubes have been accurately located.

In addition it is very desirable in radiator design that the heat transfer effected by the fins be optimised. It has been found that in the case of the prior art as shown at FIG. 1 in which the surface area of the fins have been reduced from the arrangement shown at FIG. 2 by forming the leading and trailing edges 15 and 17 respectively, to be angled at an acute angle relative to the central axis X of the tube presents the disadvantage of significantly reducing the surface area of the fins. In particular such an arrangement reduces the length of the side edges 19 of the fins. In use these side edges will be expected to be at the lower temperature when compared to the remainder of the fin when the fin is subjected to a flow of a cooling medium which passes between the fins in a direction parallel to the central axis X. In this regard it has been determined that there is a significant advantage in maximising the portions of the fins which are maintained at the lower temperatures.

The discussion throughout this specification, of the background and prior art to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia or anywhere in the world as at the priority date of the application.

DISCLOSURE OF THE INVENTION

Accordingly the invention resides in a radiator tube having a portion at each end which is adapted to be received in a header tank of a radiator and an intermediate portion between the ends, said intermediate portion having a cross section defined by a pair of side walls and a pair of end walls in which the side walls are generally parallel and have a spacing between them which is less than the spacing between the end walls, the side walls supporting a set of generally parallel fins, each fin extending laterally from the tube, each fin having an inner side edge thermally communicating with the respective side wall of the tube and an outer side edge in a substantially spaced parallel relationship with the inner side edge, a forward edge and a rear edge, said forward edge having an arcuate configuration taking the form of a continuous curve extending from the forward most edge of the fin to the outer side edge.

According to a preferred feature of the invention the rear edge of each fin has an arcuate configuration taking the form of a continuous curve from the rearmost edge to the outer side edge.

According to a preferred feature of the invention the curvature of the forward edge is part circular. According to a preferred feature of the invention the curvature of the rear edge is part circular. According to a particular embodiment of the invention the profile of the front edge of the fins define the quadrant of circle. According to a particular embodiment of the invention the profile of the rear edge of the fins define the quadrant of circle.

According to a preferred feature of the invention the fins are individually bonded to the tube.

According to a preferred feature of the invention the fins are formed integrally with the tube.

According to an alternative preferred feature of the invention the fins are formed from a folded length of material having a series of inner folds and a series of outer folds with the fins defined between the inner and outer folds wherein the inner fold is bonded to the tube and defines the inner side edge of the fins extending therefrom and the outer fold defines the outer side edge.

The invention will be more fully understood in the light of the following description of one specific embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

The description is made with reference to the accompanying drawings of which:

FIGS. 1 and 2 are illustrations of prior art to the present invention;

FIG. 3 is a cross sectional of a finned radiator tube according to the embodiment;

FIG. 4 is a cross section of a finned radiator tube according to the embodiment with comparative illustrations of the prior art fins;

FIG. 5 is an illustration of an array radiator tubes according to the embodiment in a radiator core.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENT

As in the case of the prior art as shown at FIGS. 1 and 2 and as described above, the embodiment comprises a radiator tube 111 having end portions (not shown) which have a circular cross section and which are dimensioned to be received in the header tanks of the radiator. The tubes further comprise an intermediate portion which has a generally rectangular section as shown at FIG. 3 which comprises a pair of side walls 121 which are parallel and curved end walls 125 where the central axis X of the tube which is parallel to the side walls 121 is greater in length than the axis transverse thereto.

The intermediate portion supports a set of fins 113 which are formed from a length of material which has been folded into a convoluted form to provide a series of inner folds and a series of outer folds and set of fins 113 which extend between the inner and outer folds, are generally parallel to each other and are transverse to the central longitudinal axis X of the tube to extend laterally from the sidewalls 121 of the tube. The material of which the fins comprises a suitably conductive metal such as copper or like conductive metal. The inner folds define the inner side edges of the fins and are bonded to the external face of the side walls 121 of the tube 111 and the outer folds define the outer side edges 119 of the fins and which are parallel to the inner side edges. A forward edge 115 and a rearward edge 117 is defined between the inner and outer edges.

The forward edge and rearward edges 115 and 117 respectively are curved such that they are define a quadrant of a circle having a radius corresponding to the width of the fins between the inner side edge and the outer side edge 119.

The advantage that is offered by the embodiment over the prior art as shown at FIGS. 1 and 2 and as described above comprises the circumstance that there is a significant reduction in the likelihood of injury to a worker manipulating a radiator tube according to the embodiment when installing or removing the radiator tubes into or from a radiator respectively. This is due to the absence of the sharp junction between the forward and rear trailing edges 115 and 117 and the outer side edge 119 of each fin. Therefore it is possible for worker to manipulate a radiator tube according to the embodiment with bare hands with a reduced likelihood of injury.

In addition as illustrated at FIG. 4 while the surface area of the fin is reduced when compared to the prior art as shown at FIG. 2 in which the fins have a rectangular configuration the surface area of the fins is significantly greater than those of the prior art shown at FIG. 1 where the forward and trailing rear edges 115 and 117 are angled in acute manner in respect to the central axis X of the tube. It has been determined that when comparing, the surface area of the two forms of the prior art shown at FIGS. 1 and 2 the modified form of prior art shown at FIG. 1 represents a reduction of approximately 19.4% in the surface area of the prior art fin shown at FIG. 2. By contrast the configuration of the fin of the present embodiment represents a reduction of only 8.4% from that of the prior art shown at FIG. 2.

In addition it is a feature of the function of the fins of the radiator tubes of the prior art of FIG. 1 that the temperature of the periphery of the acutely angled edge of the fin varies substantially along its length. This creates a significant inefficiency in relation to heat transfer. Contrary to conventional understanding it has been discovered that the heat transference from the fin of a radiator fin of the form of the prior art and the embodiment is not directly proportional to fin area alone. Rather has been found that the temperature gradient from the tube surface to the periphery of the fin also has an effect. Therefore the efficiency of a fin is a combination of both the fin area and temperature gradient and hence the fin profile. With the acutely angled arrangement of the prior art is shown at FIG. 1 very short temperature paths are present from the tube to the acutely angled edges. This is not conducive to good heat flow. In the case of the embodiment the temperature gradient paths are only shortly slighter than the maximum possible length as available the case of the prior art of FIG. 2. Therefore while according to conventional thinking the embodiment represents a theoretical reduction in the heat exchange efficiency of the fin of about 8.4% from that of FIG. 2, in reality the reduction is significantly less. This as a result of the front and rear edges having an arcuate configuration in order that the temperature gradient at the outer edge is maintained at a level compatible with good heat transference.

In addition as illustrated at FIG. 5 when an array of radiator tubes according to the embodiment are incorporated into a radiator core there is a clear flow path for the cooling medium through the stack of fins in a direction which is oblique to the fore and aft axis of the radiator core which serves to ensure that debris will pass through the radiator core. Furthermore the absence of any sharp edges, protrusions or corners serves to enhance the flow of debris through the radiator core.

Throughout the specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment described above. 

1. A radiator tube having a portion at each end which is adapted to be received in a header tank of a radiator and an intermediate portion between the ends, said intermediate portion having a cross section defined by a pair of side walls and a pair of end walls, the side walls are generally parallel and have a spacing between them which is less than the spacing between the end walls, each side wall of the tube supporting a set of fins, the fins being generally parallel and positioned at spaced intervals along each side to extend across each side wall between the end walls, each fin extending laterally from the tube, each fin having an inner side edge thermally communicating with the respective side wall of the tube and an outer side edge, the outer side edge being substantially parallel with the inner side edge and side wall, each fin having a forward edge and a rear edge, the forward edges and rear edges being of the fins to opposed sides of the tube being spaced from each other by the tube, the forward edge of each fin having an arcuate configuration taking the form of a continuous curve extending from the forward most edge of the fin to the outer side edge.
 2. A radiator tube as claimed at claim 1 wherein the rear edge of each fin has an arcuate configuration taking the form of a continuous curve from the rearmost edge to the outer side edge.
 3. A radiator tube as claimed at claim 2 the curvature of the rear edge is part circular.
 4. A radiator tube as claimed at claim 1 or 2 or 3 wherein the curvature of the forward edge is part circular.
 5. A radiator tube as claimed at any one of the preceding claims wherein the profile of the front edge of the fins define the quadrant of circle.
 6. A radiator tube as claimed at any one of the preceding claims wherein the profile of the rear edge of the fins define the quadrant of circle.
 7. A radiator tube as claimed at any one of the preceding claims wherein the fins are individually bonded to the tube.
 8. A radiator tube as claimed at any one of claims 1 to 7 wherein the fins are formed integrally with the tube.
 9. A radiator tube as claimed at any one of claims 1 to 7 wherein the fins are formed from a folded length of material having a series of inner folds and a series of outer folds with the fins defined between the inner and outer folds wherein the inner fold is bonded to the tube and defines the inner side edge of the fins extending therefrom and the outer fold defines the outer side edge.
 10. A radiator tube substantially as herein described with reference to the accompanying drawings.
 11. A radiator core comprising a set of radiator tubes wherein each radiator tube has a portion at each end which is adapted to be received in a header tank of a radiator and an intermediate portion between the ends, said intermediate portion having a cross section defined by a pair of side walls and a pair of end walls, the side walls are generally parallel and have a spacing between them which is less than the spacing between the end walls, each side wall of the tube supporting a set of fins, the fins being generally parallel and positioned at spaced intervals along each side to extend across each side wall between the end walls, each fin extending laterally from the tube, each fin having an inner side edge thermally communicating with the respective side wall of the tube and an outer side edge, the outer side edge being substantially parallel with the inner side edge and side wall, each fin having a forward edge and a rear edge, the forward edges and rear edges being of the fins to opposed sides of the tube being spaced from each other by the tube, the forward edge of each fin having an arcuate configuration taking the form of a continuous curve extending from the forward most edge of the fin to the outer side edge, said tubes being arrayed to define at least two substantially parallel rows of tube wherein each tube of is located to be substantially equidistant form adjacent tubes and the fins of each tube are spaced from the fins of adjacent tubes.
 12. A radiator core as claimed at claim 11 wherein the rear edge of each fin has an arcuate configuration taking the form of a continuous curve from the rearmost edge to the outer side edge.
 13. A radiator core as claimed at claim 22 the curvature of the rear edge is part circular.
 14. A radiator core as claimed at claim 1 or 12 or 13 wherein the curvature of the forward edge is part circular.
 15. A radiator core as claimed at any one of claims 11 to 14 wherein the profile of the front edge of the fins define the quadrant of circle.
 16. A radiator core as claimed at any one of claims 11 to 15 wherein the profile of the rear edge of the fins define the quadrant of circle.
 17. A radiator core as claimed at any one of claims 11 to 16 wherein the fins are individually bonded to the tube.
 18. A radiator core as claimed at any one of claims 11 to 17 wherein the fins are formed integrally with the tube.
 19. A radiator core as claimed at any one of claims 11 to 17 wherein the fins are formed from a folded length of material having a series of inner folds and a series of outer folds with the fins defined between the inner and outer folds wherein the inner fold is bonded to the tube and defines the inner side edge of the fins extending therefrom and the outer fold defines the outer side edge.
 20. A radiator core substantially as herein described with reference to the accompanying drawings. 